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http://hdl.handle.net/10773/37459
Title: | Oxygen vacancies as a link between the grain growth and grain boundary conductivity anomalies in titanium-rich strontium titanate |
Author: | Tkach, Alexander Amaral, Luís Vilarinho, Paula M. Senos, Ana M.R. |
Keywords: | Strontium titanate Grain boundary specific area Vacancies Oxygen annealing Impedance spectroscopy Charge transport Conduction mechanism |
Issue Date: | Jun-2018 |
Publisher: | Elsevier |
Abstract: | Titanium-rich (Sr/Ti = 0.995) strontium titanate (ST) ceramics, air-sintered in a temperature range of 1400–1625 °C, were reported to possess anomalies in the grain growth and analogous anomalies in the grain boundary (GB) conductivity activation energy. However, these two interface-related phenomena, occurring at GBs, could not be associated with each other using a simple “brick-layer” model. In this work we revise the topic and advocate that the deviation from the model comes from the oxygen vacancies localized at GBs of the rapidly-cooled ST ceramics. To verify this, we annealed the ceramics in oxygen and performed their systematic and comparative analysis using impedance spectroscopy. A levelling-off in the GB conductivity activation energy, which increases for ≤1.24 eV, and a four-fold decrease in the GB permittivity are observed after annealing. Thus, we confirm a key role of oxygen vacancies in relation between the grain growth and GB conductivity anomalies of as-sintered Ti-rich ST ceramics. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/37459 |
DOI: | 10.1016/j.jeurceramsoc.2018.01.014 |
ISSN: | 0955-2219 |
Appears in Collections: | CICECO - Artigos DEMaC - Artigos |
Files in This Item:
File | Description | Size | Format | |
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Oxygen Vacancies as a Link between the Grain.pdf | 790.68 kB | Adobe PDF | View/Open |
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